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Wednesday, April 11, 2007

json schema

James Clark has a great post on
XML and JSON.
But I have one point to pick at.

"JSON's primitive datatype support is weak."

First, the number issue. If you assume JSON datatypes map into JavaScript ones,
I believe the JavaScript number type does in fact have a very specific
representation. I believe, a 64 bit floating point number. Even
for integers. I'd love to point to a reference for this, but I
don't have one handy, and the
one at mozdev
is insufficient.

Note that outside of JavaScript, for languages that treat integers and
floating point as separate types, a parser can obviously distinguish between
integers and floating points and 'do the right thing' in terms of mapping
the JSON value into the appropriate type.

Next, "the set of primitive datatypes is not extensible". But this is
true for XML itself. Until you mix in XML schema. It's schema that
allows you to interpret a string in XML as some sort of other data
type. JSON has no standard schema. Yet. It's easy to imagine
though. Defined in JSON, of course.